1. Field of the Invention
This invention relates to devices employed for modifying the acoustic characteristics of large indoor areas bounded by vertical wall structure, and more particularly concerns a device which, when mounted upon at least one wall of a room achieves controlled selective diffusion and absorption of sound within said room.
2. Description of the Prior Art
It is often sought to diminish the noise level in indoor rooms, auditoriums, gymnasiums, restaurants, hallways, cafeterias, manufacturing plants and other indoor areas. In theaters where music is performed, the quality of the music heard by the audience is enhanced when the acoustic characteristics of the theater minimizes echoes, reverberations and ambient noise.
Various types of sound-absorbing rigid panel products have been employed as ceiling tiles, and various rigid and soft wall coverings have been disclosed for sound absorption. In most cases the sound-absorbing panels constitute a uniform array in their wall or ceiling installations. It has been found however, that panels intended to alter the characteristics of sound in an indoor enclosure are of greatest effectiveness when the nature and placement of the panels is custom-designed to accommodate the characteristics of the area being serviced and the type of sound encountered.
In situations where a customized sound-interactive system is being installed, it is often necessary to employ considerable trial and testing to optimize the system in terms of the types of panels employed, and their placement and interrelationships. An array of acoustic wall panels may, for example be comprised of an interactive assembly of different panels whose individual specific functions are to reflect, diffuse or absorb sound. With suitable trial and testing, the most suitable combination and arrangement may be found for the various panels.
Flat rectangular sound absorbing panels suitable for wall mounting in an abutting assemblage are disclosed in U.S. Pat. Nos. 5,644,872; 6,158,176 and elsewhere. Sound absorbing wall panels having trapezoidal or wedge shapes are disclosed in U.S. Pat. Nos. 5,141,073 and 6,209,680. Panels having a plurality of projections for the purpose of minimizing reflection of sound are disclosed in U.S. Pat. No. 3,498,405. Pyramidal panels for enhancing reflection of sound in an audience area are disclosed in U.S. Pat. No. 4,356,880.
U.S. Pat. No. 4,548,292, which concerns a floor-standing acoustic device of cylindrical shape adapted to be located in a corner of a room, discusses the difficulties in absorbing low frequency sounds, namely sounds having a frequency below 125 Hz. U.S. Pat. No. 4,319,661 discloses cylindrical acoustic devices equipped with Helmholtz resonators for absorption of low frequency sound. The Helmholtz resonators are generally defined to be comprised of a hollow chamber bounded in part by a perforated rigid panel. Although effective, Helmholtz resonators are usually heavy because of the nature of the rigid panel, which is generally of metal construction.
Although the aforementioned acoustic devices provide specialized advantages in selected installations, further improvement is needed, especially where the devices can provide versatility of performance in accommodating the specific requirements of different indoor areas.
It is accordingly an object of the present invention to provide a wall-mountable acoustic device for desirably modifying the subjectively perceived quality of sound in an indoor area.
It is another object of this invention to provide an acoustic device as in the foregoing object which is highly efficient in absorbing low frequency noise.
It is a further object of the present invention to provide an acoustic device of the foregoing object which is easily mountable upon a substantially flat wall surface.
It is a still further object of this invention to provide an assemblage of a plurality of the aforesaid acoustic devices uniformly mounted upon a vertical wall surface.
An additional object of the present invention is to provide an acoustic device of the aforesaid nature of light weight, fireproof construction amenable to low cost manufacture.
It is yet another object of this invention to provide an acoustic device of the aforesaid nature having an anesthetically pleasing appearance.
These objects and other objects and advantages of the invention will be apparent from the following description.